As the wireless communication technologies become mature in recent years, many kinds of wireless communication systems have been derived and applied to various occasions. In the public safety network architecture, in order to provide emergency communication services (e.g., to call the police, the fire station or the ambulance) or inter-group communication services, there are demands for direct communication between neighboring UEs to make the communications therebetween more efficient. However, all such demands for direct communication must be satisfied via specific UEs and specific spectrums.
The 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) communication system is a rapidest developing communication system recently, and UEs supporting the 3GPP LTE communication system have been gradually used in daily communications. In the 3GPP LTE communication system, the data transmission between UEs must be accomplished by using a base station and a core network as media, so it is required that the UEs be located in the signal coverage of the base station and the data transmission be carried out via resources allocated by the base station. If any of the UEs is not located in the signal coverage of the base station, it will be unable to get any allocated resources and, consequently, will be unable to communicate with other UEs. Additionally, since the existing 3GPP LTE communication system does not provide direct communication services between UEs, the 3GPP LTE communication system could not extend its resources to the public safety network.
Accordingly, an urgent need exists in the art to provide a resource allocation mechanism that can allocate appropriate resources of the 3GPP LTE network to UEs for direct communication.